Hexamethonium is a non-depolarising ganglionic blocker, a nicotinic nACh (NN) receptor antagonist that acts in autonomic ganglia by binding mostly in or on the NN receptor, and not the acetylcholine binding site itself. It does not have any effect on the muscarinic acetylcholine receptors (mAChR) located on target organs of the parasympathetic nervous system but acts as antagonist at the nicotinic acetylcholine receptors located in sympathetic and parasympathetic ganglia. It can act on receptors at pre-ganglionic sites in both the sympathetic and parasympathetic nervous systems, which are both regulated by nicotinic ligand-gated ionotropic acetylcholine receptors. Postganglionic sympathetic systems are usually regulated by norepinephrine, whereas parasympathetic systems are acetylcholine-based, and instead rely on muscarinic receptors.
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